NO. 23.] CENTRAL CONNECTICUT IN THE GEOLOGIC PAST. 4! 



crust, has opened to the mental vision the warfare of the resistless 

 powers which shape and reshape the surface of the world. 



Solar heat maintains the earth's water largely in fluid, and 

 the atmosphere in gaseous, form. But the concentration of solar 

 energy upon certain parts of the earth produces circulation sys- 

 tems in these mobile envelopes which work to spread out this 

 energy and lead to its dissipation. The air, most easily moved 

 by changes of temperature, carries with it from the ocean the 

 vapor of water, to be condensed in cloud and precipitated in rain, 

 and thus extends the beneficent water circulation over the surface 

 of the lands. The air sweeps along desert dust and sand; the 

 flowing waters carry away rock detritus and hold also rock sub- 

 stance in solution. The exposed portions of the crust are thus 

 impelled to sluggish changes, recorded through geologic time by 

 erosion and deposition. Movements in the four Greek elements 

 fire, air, water, and earth form a mutually dependent chain. 

 These elements become interwoven and the energy which flows 

 through them from sun to earth drags all into circulation. These 

 surface energies of the world are sun-born forces, working to 

 level the uplifted lands and extend the dominion of the sea, and 

 their control of the earth's surface is recorded by the sediments 

 piled up through geologic time. 



The earth, however, possesses forces of her own. From time 

 to time the eroded lands rise again. More locally new mountain 

 ranges are reared above the clouds, and re-invade the home of 

 Zeus. The crust of the ocean sinks lower, draws from the lands 

 the flooding waters, and restricts the rule of Poseidon to his 

 proper realm. The energies of the mysterious interior overflow, 

 and lava fields or volcanic cones add to the rocky crust above the 

 level of the sea. Thus the earth-born Titans chafe against their 

 subjugation. They are never completely conquered; and here 

 and there for a brief space of time their rebellion, as they again 

 claim dominion, spreads ruin on the earth. 



But there are disgorged from the molten rocks, which break 

 into or through the outer crust, great quantities of water vapor 

 and carbon gases with smaller quantities of other gases. Freed 

 from the pressure of the depths the gases expand to many times 

 the volume of the parent rocks. Judged by the amount of the 

 igneous rocks which have invaded the ^outer crust through geo- 



